ExcelExplorer 4.2 Online Demo
Exploring mode:
 Normal (faster)
 Memory safe (for big files)

Convert non-ASCII characters to:
 HTML numeric character references (e.g. Ӓ)
 Unicode (UTF-8)

HTML generation:
 Clip cell data

Choose an Excel file and press "Explore!" button.
Excel file:

 
Best viewed with Internet Explorer 5.0 and above.
PHP version: 5.3.29

Note that the summary information will show not only for Excel files, but for some other MS Office files